<template>
  <div class="list" ref="wrapper">
    <div>
      <div class="area">
        <div class="title border-topbottom">当前城市</div>
        <div class="button-list">
          <div class="button-wrapper">
            <div class="button">{{this.$store.state.city}}</div>
          </div>
        </div>
      </div>
      <div class="area">
        <div class="title border-topbottom">热门城市</div>
        <div class="button-list">
          <div class="button-wrapper" v-for="item of hot" :key="item.id" @click="handleCityClick(item.name)">
            <div class="button">{{item.name}}</div>
          </div>
        </div>
      </div>
      <div class="area" v-for="(item, key) of cities" :key="key" :ref="key"> <!--这里的key是ab。。。z  对象被循环时，第一项是值val，第二项是健（key）（item，key，index）of userInfo，ref用于方便refs.获取该元素区域 -->
        <div class="title border-topbottom title-letter">{{key}}</div>
        <div class="item-list" v-for="innerItem of item" :key="innerItem.id" @click="handleCityClick(innerItem.name)"> <!-- 双重循环时，只要父级key不重复，子级与父级key值重复没关系 -->
          <div class="item border-bottom">{{innerItem.name}}</div>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
import Bscroll from 'better-scroll' // 菜单列表包
export default{
  name: 'CityList',
  props: {
    hot: Array,
    cities: Object,
    letter: String
  },
  methods: {
    handleCityClick (city) {
      this.$store.commit('changeCity', city) // 触发一个changeCity方法， 把city传过去（通过commit方法直接调用mutations改变数据【省略了dispatch方法调用Actions】）
      this.$router.push('/')
      // alert(city)
    }
  },
  mounted () { // dom挂载完后执行 生命周期函数
    this.scroll = new Bscroll(this.$refs.wrapper)
  },
  watch: { // 监听器
    letter () { // 监听letter是否变化
      // console.log(this.letter)
      if (this.letter) {
        const element = this.$refs[this.letter][0] // 得到循环后的此时对应的元素区域
        // console.log(element)
        this.scroll.scrollToElement(element) // better-scroll自带方法（）中必须是dom元素或选择器
      }
    }
  }
}
</script>

<style lang="stylus" scoped>
  .border-topbottom // 希望其有上下边框
    &:before // stylus的css伪类写法 在其前面插入
      border-color #ccc // 边框颜色
    &:after // stylus的css伪类写法 在其后面插入
      border-color #ccc // 边框颜色
  .border-bottom
    &:before // stylus的css伪类写法 在前后面插入
      border-color #ccc // 边框颜色
  .title-letter
    &:hover
      background #ccc
  .list
    position absolute //绝对定位
    overflow hidden
    top 1.58rem
    left 0
    right 0
    bottom 0
    .title
      line-height .54rem
      background #eee
      padding-left .2rem
      color #666
      font-size .26rem
    .button-list
      overflow hidden
      padding .1rem .6rem .1rem .1rem
      .button-wrapper
        float left
        width 33.33%
        .button
          margin .1rem
          padding .1rem 0
          text-align center
          border .02rem solid #ccc
          border-radius .06rem
    .item-list
      .item
        line-height .76rem
        padding-left .2rem
</style>
